Copper alloy sheet material and method of producing the same

ABSTRACT

A copper alloy sheet material, having an R value of 1 or greater, which is defined by: 
         R =([ BR]+[RDW]+[W])/([C]+[S]+[B ]) 
     wherein [BR], [RDW], [W], [C], [S], and [B] represent an area ratio of crystal texture orientation component of BR orientation {3 6 2}&lt;8 5 3&gt;, RD-rotated-cube orientation {0 1 2}&lt;1 0 0&gt;, cube orientation {1 0 0}&lt;0 0 1&gt;, copper orientation {1 2 1}&lt;1 1 1&gt;, S-orientation {2 3 1}&lt;3 4 6&gt;, and brass orientation {1 1 0}&lt;1 1 2&gt;, respectively, in crystal orientation analysis in an EBSD (electron back scatter diffraction) analysis, and having a proof stress of 500 MPa or greater, and an electrical conductivity of 30%IACS or higher; and a production method of the same.

TECHNICAL FIELD

The present invention relates to a copper alloy sheet material and amethod of producing the same, and specially the present inventionrelates to a copper alloy sheet material that can be applied to leadframes, connectors, terminal materials, relays, switches, sockets, andthe like, for parts to be mounted on automotives or forelectrical/electronic equipments, and to a method of producing the same.

BACKGROUND ART

Characteristics required for copper alloy sheet materials that are usedin applications, such as lead frames, connectors, terminal materials,relays, switches, and sockets, for parts to be mounted on automotives orfor electrical/electronic equipments, include, for example, electricalconductivity, proof stress (yield stress), tensile strength, bendingproperty, and stress relaxation resistance. In recent years, thedemanded levels for those characteristics become higher, concomitantlywith the size reduction, weight reduction, enhancement of theperformance, high density packaging, or the temperature rise in the useenvironment, of electrical/electronic equipments.

Thus, under the circumstances in recent years where the copper alloysheet materials are used, changes, such as shown below, may bementioned. Firstly, since multipolarization of connectors is inprogress, along with the functional enhancements of automobiles andelectrical/electronic equipments, size reduction of an individualterminal or contact part is in progress. For example, there is anongoing movement to reduce the size of a terminal having a tab width ofabout 1.0 mm to 0.64 mm.

Secondly, under the circumstances of reduction of mineral resources orweight reduction of parts, thickness reduction of substrate materials isin progress. Further, in order to maintain the spring contact pressure,substrate materials are used which have a higher mechanical strengththan conventional cases.

Thirdly, temperature elevation in the use environment is in progress.For example, in the parts to be mounted on automotives, a decrease inthe vehicle weight is attempted, in order to reduce the amount of carbondioxide to be generated. Thus, electronic equipments, such as ECUs forengine control, which have been conventionally provided in the door, areprovided inside the engine room or in the vicinity of the engine, sothat an attempt for shortening a wire harness between the electronicequipment and the engine is being made.

Further, along with the changes described above, copper alloy sheetmaterials have problems such as described below.

Firstly, along with the size reduction of terminals, the bending radiusin bending that is applied to the contact portion or spring portion isdecreased, and the material is subjected to bending that is more severethan conventional cases. Thus, there is a problem that cracks occur inthe material.

Secondly, there is a problem that cracks occur in the material, alongwith an enhancement in the mechanical strength of the material. This isbecause the bending property of a material is generally in a trade-offrelation with mechanical strength.

Thirdly, when cracks occur at a bent portion that is applied to thecontact portion or spring portion, the contact pressure at the contactportion decreases. In that case, the contact resistance at the contactportion is enhanced, and the electrical connection is insulated, toresult in that the function as a connector is lost. Thus, this causes aserious problem.

In regard to this demand for enhancement of the bending property, someproposals are already made to solve the problem by controlling crystalorientation. It has been found in Patent Literature 1 that in regard toa Cu—Ni—Si—based copper alloy, bending property is excellent when thecopper alloy has a crystal orientation such as that the grain size andthe X-ray diffraction intensities obtained from {3 1 1}, {2 2 0} and {20 0} planes satisfy certain conditions. Further, it has been found inPatent Literature 2 that in regard to a Cu—Ni—Si-based copper alloy,bending property is excellent when the copper alloy has a crystalorientation in which the X-ray diffraction intensities obtained from {20 0} plane and {2 2 0} plane satisfy certain conditions. It has alsobeen found in Patent Literature 3 that in regard to a Cu—Ni—Si-basedcopper alloy, excellent bending property is obtained by controlling theratio of the cube orientation {1 0 0}<0 0 1>. In addition to those,Patent Literatures 4 to 8 also proposed materials which are excellent inbending property that is defined by X-ray diffraction intensities withrespect to various atomic planes. It has been found in Patent Literature4 that with regard to a Cu—Ni—Co—Si-based copper alloy, bending propertyis excellent when the copper alloy has a crystal orientation in whichthe X-ray diffraction intensity obtained from {2 0 0} plane satisfiescertain conditions against the X-ray diffraction intensities obtainedfrom {1 1 1} plane, {2 0 0} plane, {2 2 0} plane, and {3 1 1} plane. Ithas been found in Patent Literature 5 that with regard to aCu—Ni—Si-based copper alloy, bending property is excellent when thecopper alloy has a crystal orientation in which the X-ray diffractionintensities obtained from {4 2 0} plane and {2 2 0} plane satisfycertain conditions. It has been found in Patent Literature 6 that withregard to a Cu—Ni—Si-based copper alloy, bending property is excellentwhen the copper alloy has a crystal orientation which satisfies certainconditions in connection with the orientation of [1 2 3]<4 1 2>plane. Ithas been found in Patent Literature 7 that with regard to aCu—Ni—Si-based copper alloy, bending property in a Bad Way (which willbe described below) is excellent when the copper alloy has a crystalorientation in which the X-ray diffraction intensities obtained from {11 1} plane, {3 1 1} plane, and {2 2 0} plane satisfy certain conditions.Further, it has been found in Patent Literature 8 that with regard to aCu—Ni—Si-based copper alloy, bending property is excellent when thecopper alloy has a crystal orientation in which the X-ray diffractionintensities obtained from {2 0 0} plane, {3 1 1} plane, and {2 2 0}plane satisfy certain conditions.

The definitions based on the X-ray diffraction intensities in PatentLiteratures 1, 2, 4, 5, 7, and 8 are directed to the definitions of theaccumulation of particular crystal planes in the sheet plane direction(direction normal to the rolling direction, ND).

CITATION LIST Patent Literatures

Patent Literature 1: JP-A-2006-009137 (“JP-A” means unexamined publishedJapanese patent application)

Patent Literature 2: JP-A-2008-013836

Patent Literature 3: JP-A-2006-283059

Patent Literature 4: JP-A-2009-007666

Patent Literature 5: JP-A-2008-223136

Patent Literature 6: JP-A-2007-092135

Patent Literature 7: JP-A-2006-016629

Patent Literature 8: JP-A-11-335756

SUMMARY OF INVENTION Technical Problem

However, the inventions described in Patent Literatures 1 and 2 arebased on the analysis of crystal orientations by X-ray diffractionobtained from particular crystal planes, and are related only to quitelimited particular planes in the distribution of crystal orientations ofa certain extent. Further, the analysis is related only to the crystalplanes in the sheet plane direction (ND), and no control can be made onwhich crystal plane is oriented toward the rolling direction (RD) or thesheet transverse direction (TD). Thus, those techniques are stillunsatisfactory for controlling the bending property completely. Further,in the invention described in Patent Literature 3, the effectiveness inthe cube orientation has been pointed out; however, the crystalorientation components other than that are not controlled, and theimprovement of bending property has been insufficient in some cases.Also, in Patent Literatures 4 to 8, studies have been made only on theanalysis and control of the particular crystal planes or orientationsdescribed above in each case, and similarly to Patent Literatures 1 to3, the improvement of bending property is insufficient in some cases.

In view of the problems described above, an object of the presentinvention is to provide a copper alloy sheet material, which isexcellent in the bending property, and has an excellent mechanicalstrength, and which is thus suitable for lead frames, connectors,terminal materials, and the like, for electrical/electronic equipments,for connectors, for example, to be mounted on automotive vehicles, andfor terminal materials, relays, switches, and the like. Another objectis to provide a method of producing the copper alloy sheet material.

Solution to Problem

The inventors of the present invention extensively conductedinvestigations, and conducted a study on a copper alloy appropriate forelectrical/electronic part applications. Thus, the inventors found thatcracks upon bending are suppressed, by increasing the BR orientation,the RD-rotated-cube orientation (hereinafter, also referred to as RDWorientation), and the cube orientation, each of which can becharacterized by the EBSD method, and reducing the copper orientation,the S-orientation, and the brass orientation; and that the bendingproperty can be remarkably improved, when the area ratio of the crystaltexture orientation components of each of those orientations is set to apredetermined ratio. In addition to those, the inventors also found thatwhen particular additive elements are contained in the copper alloysystem, the mechanical strength or the stress relaxation resistance canbe enhanced, without loosing electrical conductivity or the bendingproperty. Thus, the inventors of the present invention have attained thepresent invention based on these findings.

That is, the present invention provides the following means:

-   (1) A copper alloy sheet material, having an R value of 1 or    greater, which is defined by:

R=([BR]+[RDW]+[W])/([C]+[S]+[B])

wherein [BR], [RDW], [W], [C], [S], and [B] represent an area ratio ofcrystal texture orientation component of BR orientation {3 6 2}<8 5 3>,RD-rotated-cube orientation {0 1 2}<1 0 0>, cube orientation {1 0 0}<0 01>, copper orientation {1 2 1}<1 1 1>, S-orientation {2 3 1}<3 4 6>, andbrass orientation {1 1 0}<1 1 2>, respectively, in crystal orientationanalysis in an EBSD (electron back scatter diffraction) analysis, and

having a proof stress of 500 MPa or greater, and an electricalconductivity of 30%IACS or higher.

-   (2) The copper alloy sheet material described in (1), having an    alloy composition comprising any one or two of Ni and Co 0.5 to 5.0    mass % in total, and Si 0.1 to 1.5 mass %, with the balance being    copper and unavoidable impurities.-   (3) The copper alloy sheet material described in (2), further    containing at least one selected from the group consisting of Sn,    Zn, Ag, Mn, B, P, Mg, Cr, Fe, Ti, Zr, and Hf 0.005 to 2.0 mass % in    total.-   (4) The copper alloy sheet material described in any one of (1) to    (3), which is a material for connectors.-   (5) A connector, which is composed of the copper alloy sheet    material described in (1) to (4).-   (6) A method of producing the copper alloy sheet material described    in any one of (1) to (5), comprising the steps of: subjecting a    copper alloy having the alloy composition to give the copper alloy,    to casting [Step 1], a homogenization heat treatment [Step 2],    hot-working [Step 3], cold-rolling [Step 6], a heat treatment [Step    7], cold-rolling [Step 8], and a final solution heat treatment [Step    9], in this order, and then subjecting the resultant copper alloy to    an aging precipitation heat treatment [Step 10],

wherein the hot-working [Step 3] is carried out, by first conducting twoor more passes of hot-rolling at a temperature from (P+30)° C. to 1,020°C. (in which P (° C.) represents the complete solid solution temperatureof solute atoms) at a working ratio per pass of 25% or higher, coolingto a temperature (P−30)° C. or lower, and then conducting two or morepasses of hot-rolling at a temperature from 400° C. to (P−30)° C. at aworking ratio per pass of 25% or lower.

-   (7) The method of producing the copper alloy sheet material    described in (6), wherein cold-rolling [Step 11] and temper    annealing [Step 12] are conducted in this order, after the aging    precipitation heat treatment [Step 10].

Advantageous Effects of Invention

The copper alloy sheet material of the present invention is excellent inthe bending property, has an excellent mechanical strength, and issuitable for lead frames, connectors, terminal materials, and the like,for electrical/electronic equipments, and for connectors, for example,to be mounted on automotive vehicles, and for terminal materials,relays, switches, and the like.

Further, the method of the present invention of producing the copperalloy sheet material is suitable as a method of producing theabove-mentioned copper alloy sheet material, which is excellent in thebending property, has an excellent Mechanical strength, and is suitablefor lead frames, connectors, terminal materials, and the like, forelectrical/electronic equipments, and for connectors, for example, to bemounted on automotive vehicles, and for terminal materials, relays,switches, and the like.

BRIEF DESCRIPTION OF DRAWINGS

{FIG. 1}

FIGS. 1( a) and 1(b) are explanatory diagrams for the method of testingthe stress relaxation resistance in the examples, in which FIG. 1( a)shows the state before heat treatment, and FIG. 1( b) shows the stateafter the heat treatment.

{FIG. 2}

FIG. 2 is a graph illustrating a typical example of the electricalconductivity change as a result of elevation in the heat treatmenttemperature, and the graph schematically illustrates a method ofdetermining the temperature (P) ° C. at which the solute atoms arecompletely made into a solid solution thereby.

MODE FOR CARRYING OUT THE INVENTION

Preferable embodiments of the copper alloy sheet material of the presentinvention will be described in detail. Herein, the term “copper alloymaterial” means a product obtained after a copper alloy base material isworked into a predetermined shape (for example, sheet, strip, foil, rod,or wire). Among them, a sheet material refers to a material which has aspecific thickness, is stable in the shape, and is extended in the planedirection, and in a broad sense, the sheet material is meant toencompass a strip material. Herein, with regard to the sheet material,the term “surface layer of the material (or material surface layer)”means the “sheet surface layer,” and the term “position of a depth ofthe material” means the “position in the sheet thickness direction.”There are no particular limitations on the thickness of the sheetmaterial, but when it is considered that the thickness should wellexhibit the effects of the present invention and should be suitable forpractical applications, the thickness is preferably 8 to 800 μm, andmore preferably 50 to 70 μm.

In the copper alloy sheet material of the present invention, thecharacteristics are defined by the accumulation ratio of the atomicplane in a predetermined direction of a rolled sheet, but this will beconsidered enough if the copper alloy sheet material has suchcharacteristics. The shape of the copper alloy sheet material is notintended to be limited to a sheet material or a strip material, and itis noted that in the present invention, a tube material can also beconstrued and treated as a sheet material.

In order to clarify the cause of the occurrence of cracks upon bendingof a copper alloy sheet material, the inventors of the present inventionconducted a detailed investigation on the metal texture of the materialafter bending deformation. As a result, it was observed that thesubstrate material is not deformed uniformly, but non-uniformdeformation proceeds, in which deformation is concentrated only in aregion of a particular crystal orientation. Further, we found that, dueto that non-uniform deformation, wrinkles of a depth of severalmicrometers or micro-cracks occur, at the surface of the substratematerial after bending.

Further, we found that when there are many of the BR orientation, theRDW orientation, and the cube orientation, and there are fewer of thecopper orientation, the S-orientation, and the brass orientation,non-uniform deformation is suppressed, and the wrinkles that occur atthe surface of the substrate material are reduced, so that cracks aresuppressed.

In the observation of the texture of a bent cross-section, we alsoconfirmed that there are fewer local deformation bands observed in thegrains of the BR orientation, the RDW orientation, and the cubeorientation, and there are more local deformation bands observed in thegrains of the copper orientation, the S-orientation, and the brassorientation.

(Definition by EBSD Analysis)

When the area ratios of the respective crystal texture orientationcomponents of the BR orientation {3 6 2}<8 5 3>, the RD-rotated-cubeorientation {0 1 2}<1 0 0>, the cube orientation {1 0 0}<0 0 1>, thecopper orientation {1 2 1}<1 1 1>, the S-orientation {2 3 1}<3 4 6>, andthe brass orientation {1 1 0}<1 1 2>, as defined by the EBSD method, aredesignated as [BR], [RDW], [W], [C], [S], and [B], respectively, when Rthat is defined by: R=([BR]+[RDW]+[W])/([C]+[S]+[B]) is 1 or greater,the effects described above can be obtained. The value of R ispreferably 1.1 or greater, more preferably from 1.2 to 6. Any techniqueshave not been hitherto known to simultaneously control the area ratiosof the atomic planes having these orientations.

Herein, the method of indicating the crystal orientation in the presentspecification is such that a Cartesian coordinate system is employed,representing the rolling direction (RD) of the material in the X-axis,the transverse direction (TD) in the Y-axis, and the direction normal tothe rolling direction (ND) in the Z-axis, various regions in thematerial are indicated in the form of (h k I) [u v w], using the index(h k l) of the crystal plane that is perpendicular to the Z-axis(parallel to the rolled plane) and the index [u v w] in the crystaldirection parallel to the X-axis. Further, the orientation that isequivalent based on the symmetry of the cubic crystal of a copper alloyis indicated as {h k I}<u v w>, using parenthesis symbols representingfamilies, such as in (1 3 2) [6 −4 3], and (2 3 1) [3 −4 6]. The sixkinds of orientations according to the present invention arerespectively expressed by the indices such as described above.

The analysis of the crystal orientation in the present invention isconducted using the EBSD method. The EBSD method, which stands forElectron Back Scatter Diffraction, is a technique of crystal orientationanalysis using reflected electron Kikuchi-line diffraction (Kikuchipattern) that occurs when a sample is irradiated with an electron beamunder a scanning electron microscope (SEM). In the present invention, asample area measured 500 μm on each of the four sides and containing 200or more grains, was subjected to an analysis of the orientation, byscanning in a stepwise manner at an interval of 0.5 μm.

In the present invention, the grains having orientation components ofthe texture of each of the above BR orientation, RD-rotated-cube (RDW)orientation, cube (W) orientation, copper (C) orientation, Sorientation, and brass (B) orientation and the area of the planes ofatoms thereof are defined in connection with whether the grains and thearea are within the range of the predetermined deviation angle that willbe described below.

In regard to the deviation angle from the ideal orientation representedby the above-mentioned index, for (i) the crystal orientation at eachmeasurement point and (ii) any one of the BR-orientation,RDW-orientation, cube-orientation, copper-orientation, S-orientation,and brass-orientation as an ideal orientation as an object measurement,an angle of rotation around the axis of rotation that is common to (i)and (ii) is calculated, and the angle of rotation is designated as thedeviation angle. For example, with regard to the S-orientation (2 3 1)[6 −4 3], the orientation (1 2 1) [1 −1 1] is in a relationship of beingrotated by 19.4° around the (20 10 17) direction as the axis ofrotation, and this angle is designated as the deviation angle. Thecommon axis of rotation consists of three integers of 40 or less, butthe integer that can be expressed with the smallest deviation angleamong the integers of 40 or less is employed. This deviation angle iscalculated for all measurement points, and the number including up tothe first decimal place is designated as the effective number. The areaof grains having an orientation within 10° from the respective deviationangle of the BR-orientation, RDW-orientation, cube-orientation,copper-orientation, S-orientation, and brass-orientation is divided bythe total measured area, and the resultant value is designated as theratio of the area (area ratio) of atomic planes having the respectiveorientation.

The data obtained from the orientation analysis based on EBSD includesthe orientation data to a depth of several tens nanometers, throughwhich the electron beam penetrates into the sample. However, since thedepth is sufficiently small as compared with the width to be measured,the data is described in terms of ratio of an area, i.e. area ratio, inthe present specification.

Since EBSD measurement is used for the analysis of crystal orientation,this is largely different from the measurement of the accumulation ofparticular atomic plane(s) against the plane direction (ND) according tothe conventional X-ray diffraction method, and three-dimensional crystalorientation data that is closer to the complete one is obtained withhigher resolution power. Therefore, it is possible to obtain completelynovel finding on the crystal orientation that governs bending property.

In regard to the EBSD analysis, in order to obtain a clear Kikuchi-linediffraction image, it is preferable to mirror polish the substratesurface, with polishing particles of colloidal silica after mechanicalpolishing, and then to conduct the analysis. Further, the measurement isconducted from the sheet surface.

(Alloy Composition and the Like) Ni, Co, Si

As the material of the present invention for connectors, copper or acopper alloy is used. As a material having electrical conductivity,mechanical strength, and heat resistance that are required ofconnectors, use can be preferably made of any of copper alloys, such asphosphor bronze, brass, nickel silver, beryllium copper, andCorson-based alloys (Cu—Ni—Si-based), as well as copper. Particularly,when it is desired to obtain an area ratio which satisfies the specificrelation of crystal orientation accumulation according to the presentinvention, pure copper-based materials, or precipitate-type alloysincluding beryllium copper and Corson-based alloys are preferred.Further, in order to achieve a balance between high mechanical strengthand high electrical conductivity, which is required of high-techsmall-sized terminal materials, Cu—Ni—Si-based, Cu—Ni—Co—Si-based, andCu—Co—Si-based precipitate-type copper alloys are preferred.

This is because, in solid solution-type alloys, such as phosphor bronzeand brass, there are fewer micro-regions having the cube orientation incold-rolled materials, while the micro-regions serve as the nuclei ofthe cube orientation grain growth in the growth of grains upon a heattreatment. This is because, in a system having low accumulation defectenergy, such as phosphor bronze or brass, shear bands are likely todevelop upon cold-rolling.

In the present invention, when the respective amounts of addition ofnickel (Ni), cobalt (Co), and silicon (Si), which form the first groupof elements to be added to copper (Cu), are brought under control,Ni—Si, Co—Si, and/or Ni—Co—Si compounds can be precipitated, to therebyenhance the mechanical strength of the resultant copper alloy. Thecontents of any one of or two of Ni and Co are, in total, preferablyfrom 0.5 to 5.0 mass %, more preferably 0.6 to 4.5 mass %, and stillmore preferably 0.8 to 4.0 mass %. The content of Ni is preferably 1.5to 4.2 mass %, more preferably 1.8 to 3.9 mass %; and the content of Cois preferably 0.3 to 1.8 mass %, more preferably 0.5 to 1.5 mass %. Inthe case where it is desired to increase the electrical conductivity, itis preferable to essentially add Co. If the amounts of addition of thoseelements of Ni, Co and Si in total are too large, the electricalconductivity is apt to be decreased, and if the amounts of addition aretoo small, the mechanical strength is apt to be insufficient. Further,the content of Si is preferably 0.1 to 1.5 mass %, more preferably 0.2to 1.2 mass %. Further, since Co is a rare element, and since Co raisesthe solution temperature when added in a given amount, if it is notnecessary to significantly increase electrical conductivity depending onthe use, it is preferable not to add Co.

Other Elements

Next, the effects of additive elements that enhance the characteristics(secondary characteristics), such as stress relaxation resistance, willbe described. Preferable examples of the additive element include Sn,Zn, Ag, Mn, B, P, Mg, Cr, Fe, Ti, Zr, and Hf. In order to sufficientlyutilize the effects of addition thereof and to prevent a decrease in theelectrical conductivity, the additive element(s) needs to be added, in atotal amount, of preferably 0.005 to 2.0 mass %, more preferably 0.01 to1.5 mass %, and further preferably 0.03 to 0.8 mass %. If the totalamount of these additive elements is too large, it becomes the cause ofan adverse affection of decreasing the electrical conductivity. If thetotal amount of these additive elements is too small, the effects ofadding these elements are hardly exhibited.

The effects of adding various additive elements will be described below.Mg, Sn, and Zn improve the stress relaxation resistance when added toCu—Ni—Si-based, Cu—Ni—Co—Si-based, and Cu—Co—Si-based copper alloys.When these elements are added together, as compared with the case whereany one of them is sorely added, the stress relaxation resistance isfurther improved by synergistic effects. Further, an effect ofremarkably improving solder brittleness is obtained.

Mn, Ag, B, and P, when added, improve hot-workability, and at the sametime, enhance the mechanical strength.

Cr, Fe, Ti, Zr, and Hf finely precipitate in the form of compounds withNi, Co, and/or Si, which are main elements to be added, or in the formof simple elements, to contribute to precipitation hardening. Further,these elements precipitate in the form of compounds having a size of 50to 500 nm, and suppress grain growth, thereby having an effect of makingthe grain size fine and making the bending property satisfactory.

Next, the method of the present invention of producing the copper alloysheet material (method of controlling the crystal orientation of thematerial) will be explained. Herein, the explanation will be given bytaking a sheet material (strip material) of a precipitate-type copperalloy as an example, but the method can be applied tosolid-solution-type alloy materials, dilute-based alloy materials, andpure copper-based materials.

Generally, a precipitate-type copper alloy is produced by working aningot that has been subjected to a homogenizing heat treatment into athin sheet at the steps of hot-rolling and cold-rolling, conducting afinal solution heat treatment at a temperature in the range of 700 to1,020° C. to make the solute atoms into a solid solution again, and thenconducting an aging precipitation heat treatment and finishcold-rolling, thereby to satisfy the required mechanical strength. Theconditions for the aging precipitation heat treatment and the finishcold-rolling are adjusted, in accordance with the desiredcharacteristics, such as mechanical strength and electricalconductivity. The texture of the resultant copper alloy is approximatelydetermined by the recrystallization occurring in the final solution heattreatment in this series of steps, and is finally determined by therotation of orientation occurring in the finish rolling.

Examples of the method of producing the copper alloy sheet material ofthe present invention include a method of obtaining the copper alloysheet material of the present invention by carrying out [Step 1] to[Step 12] in the following order: that is, melting a copper alloy rawmaterial formed from a predetermined alloying element composition in ahigh-frequency melting furnace, followed by casting this molten productto obtain an ingot [Step 1]; subjecting the ingot to a homogenizationheat treatment at 1,020 to 700° C. for 10 minutes to 10 hours [Step 2];conducting two or more passes of hot-rolling at a temperature in therange of 1,020° C. to (P+30)° C. at a working ratio of 25% or higher perpass [Step 3-1]; cooling the resultant hot-rolled sheet to a temperature(P−30)° C. or lower by air cooling or water cooling [Step 3-2];conducting two or more passes of hot-rolling at a temperature in therange of (P−30)° C. to 400° C. at a working ratio of 25% or less perpass [Step 3-3]; water cooling [Step 4]; face milling [Step 5];cold-rolling at a working ratio of 50 to 99% [Step 6]; a heat treatmentof maintaining at 600 to 900° C. for 10 seconds to 5 minutes [Step 7];cold-working at a working ratio of 5 to 55% [Step 8]; and a finalsolution heat treatment of maintaining at 750 to 1,000° C. for 5 secondsto 1 hour [Step 9]; then carrying out an aging precipitation heattreatment at 350 to 600° C. for 5 minutes to 20 hours [Step 10]; finishrolling at a working ratio of 2 to 45% [Step 11]; and temper annealingof maintaining at 300 to 700° C. for 10 seconds to 2 hours [Step 12].

TABLE A Step (1) Step 2 Step 3-1 Step 3-3 Step 4 Step 5 Step 6 Step 7Step 8 Step 9 Homogenization Hot-rolling Step 3-2 Hot-rolling WaterSurface Cold- Intermediate Cold- Final solution treatment (1) Cooling(2) cooling milling rolling heat treatment rolling heat treatmentTemperature ° C. 700 to 1,020 (P + 30) to (P − 30) 400 to — — — 600 to900 — 750 to 1,000 1,020 (P − 30) Working ratio % — >25% — <25% — — 50to 99 — 5 to 55 — 2 or more 2 or more passes passes Time period* 10 m to10 h — — — — — — 10 s to 5 m — 1 s to 1 h Step (2) Step 10 Step 11 Step12 Aging precipitation Cold- Temper heat treatment rolling annealingTemperature ° C. 350 to 600 — 300 to 700 Working ratio % — 2 to 45 —Time period* 5 m to 20 h — 10 s to 2 h *s: sec., m: min., and h: hour

The copper alloy sheet material of the present invention is preferablyproduced by the production method of the above-described embodiment, butif the abode-described R according to a crystal orientation analysis inEBSD measurement, satisfies the defined conditions, the method is notnecessarily restricted to have all of the [Step 1] to [Step 12] in thesequence described above. Although included in the method describedabove, a method which is terminated at, for example, [Step 10] as thefinal step among the above-described [Step 1] to [Step 12], is alsoacceptable. Alternatively, any one or two or more of the [Step 10] to[Step 12] may also be repeatedly carried out two or more times. Forexample, before the [Step 10] is carried out, cold-rolling at a workingratio of 2 to 45% [Step 11′] may be carried out.

When the completion temperature of the hot-rolling [Step 3-3] is low,the speed of precipitation decreases, thus water cooling [Step 4] is notnecessarily required. At what temperature or lower the hot-rollingshould be finished so that water cooling would be unnecessary, wouldvary depending on the alloy concentration or the amount of precipitationin the hot-rolling, and it may be appropriately selected. Face milling[Step 5] may be omitted, depending on the degree of scales occurred onthe material surface after the hot-rolling. Further, the scales may beremoved, by dissolution with acid washing or the like.

There are occasions in which high-temperature rolling that is carriedout at or above the dynamic recrystallization temperature is termed ashot-rolling, and high-temperature rolling that is carried out at a hightemperature from the room temperature or higher to the dynamicrecrystallization temperature or lower is termed as warm rolling.However, it is general to collectively refer to the two processes ashot-rolling. In the present invention as well, the two processes arecollectively referred to as hot-rolling.

In the production method of the copper alloy sheet material of thepresent invention, in the final solution heat treatment, in order todecrease the area ratios of the brass orientation, the S-orientation,and the copper orientation, and to increase the area ratios of the BRorientation, the RDW orientation, and the cube orientation, it ispreferable to select the conditions described above in the hot-workingthat is carried out after homogenizing the ingot ([Step 3] composed of[Step 3-1] to [Step 3-3]). In usual production methods for conventionalcopper alloys, a high-temperature working to be carried out afterhomogenization is conducted at a temperature as high as possible, forthe purpose of lowering deformation resistance, or in the case ofprecipitate-type alloys, for the purpose of suppressing precipitation ina large quantity. On the other hand, the method of producing the copperalloy sheet material of the present invention is characterized in thathot-rolling ([Step 3-1]) is carried out as a first hot-rolling step, andthen cooling ([Step 3-2]) is conducted, and re-hot-rolling ([Step 3-3])is carried out as a second hot-rolling step, at a temperature lower thanthat of the first step. Further, the temperature of these first step andsecond step are defined to be in a specific temperature range that isdefined by using P° C., which is the temperature at which solute atomsare completely made into a solid solution.

The temperature in the first hot-rolling step is 1,020° C. to (P+30)° C.Due to high-temperature brittleness when this temperature is too high,and on the other hand, due to not occurring destruction of the casttexture by recrystallization when the temperature is too low, cracks mayoccur in each case. Preferably, the temperature is 1,000° C. to (P+50)°C., more preferably 980° C. to (P+70)° C.

The temperature in the second hot-rolling step is (P−30)° C. to 400° C.Due to that the resultant texture is equivalent to that obtained viaconventional and usual rolling when this temperature is too high, and onthe other hand, due to intermediate-temperature brittleness when thetemperature is too low, cracks may occur in each case. Preferably, thetemperature is (P−50)° C. to 450° C., more preferably (P−70)° C. to 500°C.

It is preferable that the temperature of the first hot-rolling step (T1)be higher than the temperature of the second hot-rolling step (T2)(T1>T2), and to take a typical example, the difference between the twotemperatures (T1−T2) is preferably 60 to 100° C., more preferably 100 to140° C.

Further, in the production method of the present invention, it isimportant to provide the cooling step in the mid course of the firsthot-rolling step and the second hot-rolling step. The cooling end-pointtemperature is (P−30)° C. or lower, and although the lower limittemperature is not particularly limited, the lower limit is practically450° C. or higher. The technical significance of this cooling step willbe described herein. The temperature range between T1 and T2 that aredefined by using P° C. is a temperature range in which precipitation ofsolute elements occurs most rapidly. On the other hand, at a temperaturehigher than this intermediate temperature range, since the soluteelements are made into a solid solution, the diffusion of atoms is slowat a temperature lower than this intermediate temperature range, andcoarsening of the precipitate occurs only slightly. When the alloymaterial is subjected to rolling at a temperature in this intermediatetemperature range, the progress of precipitation is further acceleratedby an increase in the lattice defects, and thus coarse precipitateshaving a size of around submicron scale are formed. In the subsequentcold-rolling, since strain is concentrated in the surrounding of thesecoarse precipitate particles having a size of around severalmicrometers, in the intermediate solution heat treatment, recrystallizedgrains of random orientations are formed from the high strain regionaround the particles, and the desired area ratio of orientations may notbe obtained. That is, in order to achieve the area ratio of orientationsas defined in the present invention, it is important to control coarseprecipitate particles that cause randomization of orientations, and inorder to do so, it is preferable not to conduct rolling at a temperaturein the intermediate temperature range described above.

Further, in the production method of the present invention, theintermediate heat treatment that is carried out after the hot-rollinghas a significant meaning. It is preferable to conduct the intermediateheat treatment at a temperature of 600 to 900° C. in the mid course ofcold-rolling as explained above. As such, by employing the intermediateheat treatment step, a texture in which the entire plane has not beenrecrystallized can be obtained. That is, even among the crystalorientations in the rolled material, there are crystal orientationswhich are restored fast, and crystal orientations which are restoredslowly. Therefore, due to such a difference, a non-uniformlyrecrystallized texture is formed. This non-uniformity that isintentionally introduced accelerates the preferential development of arecrystallized crystal texture in the intermediate recrystallizationheat treatment [Step 9].

The temperature P° C. at which solute atoms are completely made into asolid solution is determined according to a usual method as describedbelow. That is, an ingot is homogenized for 1 hour at 1,000° C.,followed by subjecting to hot-rolling and cold-rolling to give a sheetmaterial. Then, the sheet material is subjected to a heat treatment ofmaintaining in a salt bath for 30 seconds in each increment of 10° C. upto 700 to 1,000° C., followed by water quenching, to thereby freeze thesolid solution state and the precipitation state at each temperature, tomeasure the electrical conductivity. The thus-measured electricalconductivity is used as an alternative characteristic of the amount ofelements made into a solid solution, and the temperature at which thedecrease of the electrical conductivity that is accompanied by elevationin the heat treatment temperature is saturated, is defined as thecomplete solid solution temperature, P° C. Typical electricalconductivity changes, and the method of determining the temperature P (°C.) in accordance therewith are schematically presented in FIG. 2. Totake a typical example, the temperature P is practically 750 to 950° C.

The one-pass working ratio (i.e. working ratio per pass) in the firsthot-rolling step is preferably 25% or higher. If this is too low,destruction of the cast texture may not occur. The upper limit may varydepending on the specifications of the rolling machine to be utilized,and there are no particular limitations on the upper limit; however, theupper limit is generally 50% or lower.

The one-pass working ratio in the second hot-rolling step is preferably25% or lower. If this is too high, since the working is conducted at arelatively low temperature, working cracks may occur. The lower limit isnot particularly limited, but in view of operation efficiency, the lowerlimit is generally 3% or higher.

The copper alloy sheet material of the present invention can satisfy thecharacteristics required, for example, of a copper alloy sheet materialfor use in connectors. In particular, the copper alloy sheet materialcan realize such favorable characteristics that the 0.2% proof stress is500 MPa or greater (preferably 600 MPa or greater, and particularlypreferably 700 MPa or greater); the bending property, in terms of thevalue (r/t) obtained by dividing the minimum bending radius (r: mm)capable of bending without cracks in the 90° W bending test, by thesheet thickness (t: mm), is 1 or less; and the electrical conductivityis 30%IACS or greater (preferably 35%IACS or greater, and particularlypreferably 40%IACS or greater); and further, the stress relaxationresistance, in terms of a stress relaxation ratio (SR), can be 30% orless (preferably, 25% or less), as determined by the measurement methodof maintaining the material at 150° C. for 1,000 hours as will bedescribed below.

EXAMPLES

The present invention will be described in more detail based on examplesgiven below, but the invention is not meant to be limited by these.

Example 1

As shown with the respective composition in the column of alloyingelements in Table 1-1, an alloy containing at least one or both of Niand Co in an amount of 0.5 to 5.0 mass % in total, and Si in an amountof 0.1 to 1.5 mass %, with the balance being Cu and unavoidableimpurities, was melted in a high-frequency melting furnace, followed bycasting, to obtain an ingot. The resultant ingots in this state wereused as test materials, and test specimens of copper alloy sheetmaterials of Examples 1-1 to 1-19 according to the present invention andComparative Examples 1-1 to 1-9 were produced in any of the following Ato F.

(Step A)

Each of the test specimens was produced in the following manner. Therespective test material was subjected to a homogenization heattreatment at 1,020 to 700° C. for 10 minutes to 10 hours; three passesof hot-rolling at a working ratio of 25% or higher at a temperature inthe range of 1,020° C. to (P+30)° C.; air cooling; three passes ofhot-rolling at a working ratio of 25% or lower at a temperature in therange of (P−30)° C. to 400° C.; water cooling; cold-rolling at a workingratio of 50% to 99%; a heat treatment of maintaining at 600 to 900° C.for 10 seconds to 5 minutes; cold-working at a working ratio of 5 to55%; and a final solution heat treatment of maintaining at 750 to 1,000°C. for 5 seconds to 1 hour. Then, the resultant sheet was subjected toan aging precipitation heat treatment at 350 to 600° C. for 5 minutes to20 hours; finish rolling at a working ratio of 2 to 45%; and temperannealing of maintaining at 300 to 700° C. for 10 seconds to 2 hours.

(Step B)

Each of the test specimens was produced in the following manner. Therespective test material was subjected to a homogenization heattreatment at 1,020 to 700° C. for 10 minutes to 10 hours; three passesof hot-rolling at a working ratio of 25% or higher at a temperature inthe range of 1,020° C. to (P+30)° C.; air cooling; three passes ofhot-rolling at a working ratio of 25% or lower at a temperature in therange of (P−30)° C. to 400° C.; water cooling; cold-rolling at a workingratio of 50% to 99%; a heat treatment of maintaining at 600 to 900° C.for 10 seconds to 5 minutes; cold-working at a working ratio of 5 to55%; and a final solution heat treatment of maintaining at 750 to 1,000°C. for 5 seconds to 1 hour. Then, the resultant sheet was subjected torolling at a working ratio of 2 to 45%; an aging precipitation heattreatment at 350 to 600° C. for 5 minutes to 20 hours; finish rolling ata working ratio of 2 to 45%; and temper annealing of maintaining at 300to 700° C. for 10 seconds to 2 hours.

(Step C)

Each of the test specimens was produced in the following manner. Therespective test material was subjected to a homogenization heattreatment at 1,020 to 700° C. for 10 minutes to 10 hours; three passesof hot-rolling at a working ratio of 25% or higher at a temperature inthe range of 1,020° C. to (P+30)° C.; air cooling; three passes ofhot-rolling at a working ratio of 25% or lower at a temperature in therange of (P−30)° C. to 400° C.; water cooling; cold-rolling at a workingratio of 50% to 99%; a heat treatment of maintaining at 600 to 900° C.for 10 seconds to 5 minutes; cold-working at a working ratio of 5 to55%; and a final solution heat treatment of maintaining at 750 to 1,000°C. for 5 seconds to 1 hour. Then, the resultant sheet was subjected toan aging precipitation heat treatment at 350 to 600° C. for 5 minutes to20 hours.

(Step D)

Each of the test specimens was produced in the following manner. Therespective test material was subjected to a homogenization heattreatment at 1,020 to 700° C. for 10 minutes to 10 hours; three passesof hot-rolling at a working ratio of 25% or higher at a temperature inthe range of 1,020° C. to (P+30)° C.; air cooling; three passes ofhot-rolling at a working ratio of 25% or lower at a temperature in therange of (P−30)° C. to 400° C.; water cooling; cold-rolling at a workingratio of 50% to 99%; a heat treatment of maintaining at 600 to 900° C.for 10 seconds to 5 minutes; cold-working at a working ratio of 5 to55%; and a final solution heat treatment of maintaining at 750 to 1,000°C. for 5 seconds to 1 hour. Then, the resultant sheet was subjected torolling at a working ratio of 2 to 45%; and an aging precipitation heattreatment at 350 to 600° C. for 5 minutes to 20 hours.

(Step E)

Each of the test specimens was produced in the following manner. Therespective test material was subjected to a homogenization heattreatment at 1,020 to 700° C. for 10 minutes to 10 hours; three passesof hot-rolling at a working ratio of 25% or higher at a temperature inthe range of 1,020° C. to (P+30)° C.; air cooling; three passes ofhot-rolling at a working ratio of 25% or lower at a temperature in therange of (P−30)° C. to 400° C.; water cooling; cold-rolling at a workingratio of 50% to 99%; and a final solution heat treatment of maintainingat 750 to 1,000° C. for 5 seconds to 1 hour. Then, the resultant sheetwas subjected to an aging precipitation heat treatment at 350 to 600° C.for 5 minutes to 20 hours; finish rolling at a working ratio of 2 to45%; and temper annealing of maintaining at 300 to 700° C. for 10seconds to 2 hours.

(Step F)

Each of the test specimens was produced in the following manner. Therespective test material was subjected to a homogenization heattreatment at 1,020 to 700° C. for 10 minutes to 10 hours; three passesof hot-rolling at a working ratio of 25% or higher at a temperature inthe range of 1,020° C. to (P+30)° C.; water cooling; cold-rolling at aworking ratio of 50% to 99%; a heat treatment of maintaining at 600 to900° C. for 10 seconds to 5 minutes; cold-working at a working ratio of5 to 55%; and a final solution heat treatment of maintaining at 750 to1,000° C. for 5 seconds to 1 hour. Then, the resultant sheet wassubjected to an aging precipitation heat treatment at 350 to 600° C. for5 minutes to 20 hours; finish rolling at a working ratio of 2 to 45%;and temper annealing of maintaining at 300 to 700° C. for 10 seconds to2 hours.

TABLE B Step (1) Homogenization Hot-working Air Hot-working WaterIntermediate Cold- Solution treatment (1) *1 cooling (2) *1 cooling heattreatment rolling treatment Step A Ex ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Step B Ex ◯ ◯ ◯ ◯◯ ◯ ◯ ◯ Step C Ex ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Step D Ex ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ Step E C Ex◯ ◯ ◯ ◯ ◯ — — ◯ Step F C Ex ◯ ◯ — — ◯ ◯ ◯ ◯ Step (2) Cold- Aging Cold-Temper rolling treatment rolling annealing Step A Ex — ◯ ◯ ◯ Step B Ex ◯◯ ◯ ◯ Step C Ex — ◯ — — Step D Ex ◯ ◯ — — Step E C Ex — ◯ ◯ ◯ Step F CEx — ◯ ◯ ◯ “Ex” means Example according to the present invention, and “CEx” means Comparative Example. *1 The case where the conditions fallwithin the ranges defined in Table A, is indicated as “◯”; the casewhere the conditions fall outside the ranges defined in Table A, isindicated as “X”; and other items, if carried out, are indicated as “◯”.

After the respective heat treatment or rolling above, acid washing orsurface polishing was conducted according to the state of oxidation orroughness of the material surface, and correction with a tension levelerwas conducted according to the shape.

The thus-obtained test specimens were subjected to examination of theproperties as described below. Herein, the thickness of the respectivetest specimen was set at 0.15 mm. The results of Examples according tothe present invention are shown in Table 1-1, and those of ComparativeExamples are shown in Table 1-2.

a. Area ratios of the regions of BR orientation, RDW orientation, cubeorientation, copper orientation, S orientation, and brass orientation:

The measurement was conducted with the EBSD method in a measurementregion of about 500 μm on each of the four sides, under the conditionsof a scan step of 0.5 μm. The measured area was adjusted on the basis ofthe condition of inclusion of 200 or more grains. As explained above,with respect to the atomic planes of grains having a deviation angle of10° or less in each of the ideal orientations, the area of an atomicplane having each orientation was determined, and the area ratio (R) wascalculated by the following equation:

R=([BR]+[RDW]+[W])/([C]+[S]+[B]).

b. Bending property:

A sample was taken, by cutting out from the respective test specimenperpendicularly to the rolling direction, into a size with width 10 mmand length 25 mm. The respective sample was subjected to W bending suchthat the axis of bending would be perpendicular to the rollingdirection, which is designated as GW (Good Way), and separatelysubjected to W bending such that the axis of bending would be parallelto the rolling direction, which is designated as BW (Bad Way). Theoccurrence (i.e. presence or absence) of cracks at the thus-bent portionwas examined, by observing the bent portion under an optical microscopewith a magnification of 50.

A sample which had no crack at the bent portion and had minor wrinklesis rated as “{circle around (•)}” (good), a sample which had no crackbut had large wrinkles, although they cause no practical problems, israted as “o” (fair), and a sample which had cracks is rated as “x”(poor). The bending angle at the respective bent portion was set at 90°,and the inner radius of the respective bent portion was set at 0.15 mm.

c. 0.2% proof stress [YS]:

Three test specimens that were cut out from the direction parallel tothe rolling direction, according to JIS Z2201-13B, were measuredaccording to JIS Z2241, and the 0.2% proof stress (yield stress) isshown as an average value of the results.

d: Electrical conductivity [EC]:

The electrical conductivity was calculated by using the four-terminalmethod to measure the specific resistance of the material in athermostat bath that was maintained at 20° C. (±0.5° C.). The spacingbetween terminals was set to 100 mm.

e. Stress relaxation ratio [SR]:

The stress relaxation ratio was measured, according to JCBA T309:2001 ofthe Japan Copper and Brass Association (which is a provisional standard;the former standard was the “Electronic Materials Manufacturer'sAssociation of Japan Standard EMAS-3003”), under the conditions ofmaintaining at 150° C. for 1,000 hours, as shown in the below. Aninitial stress that was 80% of the yield stress (proof stress) wasapplied, by the cantilever method.

FIGS. 1( a) and 1(b) each are a drawing explaining the method of testingthe stress relaxation resistance, in which FIG. 1( a) shows the statebefore heat treatment, and FIG. 1( b) shows the state after the heattreatment. As shown in FIG. 1( a), the position of a test specimen 1when an initial stress of 80% of the proof stress was applied to thetest specimen 1 cantilevered on a test bench 4, is defined as thedistance δ₀ from the reference position. This test specimen was kept ina thermostat at 150° C. for 1,000 hours (which corresponds to the heattreatment at the state of the test specimen 1). The position of the testspecimen 2 after removing the load, is defined as the distance H_(t)from the reference position, as shown in FIG. 1( b). The referencenumeral 3 denotes the test specimen to which no stress was applied, andthe position of the test specimen 3 is defined as the distance H₁ fromthe reference position. Based on the relationships between thosepositions, the stress relaxation ratio (%) was calculated as:{(H_(t)−H₁)/(δ₀−H₁)}×100. In the formula, δ₀ represents the distancefrom the reference position to the test specimen 1; H₁ represents thedistance from the reference position to the test specimen 3; and H_(t)represents the distance from the reference position to the test specimen2.

TABLE 1-1 Alloying elements Bending ID Ni Co Si property YS EC SR numbermass % mass % mass % Step R GW BW MPa % IACS % Ex 1-1 0.49 1.02 0.37 B1.3 ◯ ◯ 626 55.0 24.6 Ex 1-2 0.98 0.51 0.39 D 1.5 ◯ ◯ 682 52.1 24.0 Ex1-3 — 0.82 0.46 C 1.8 ◯

655 53.9 24.1 Ex 1-4 0.49 1.53 0.36 A 1.4 ◯ ◯ 687 52.8 24.7 Ex 1-5 0.781.22 0.43 B 1.3 ◯ ◯ 680 51.8 22.9 Ex 1-6 0.98 1.02 0.49 D 1.6 ◯ ◯ 70050.6 24.1 Ex 1-7 2.27 — 0.66 C 2.1 ◯

732 41.1 25.7 Ex 1-8 0.88 1.73 0.62 A 1.7

◯ 797 47.2 24.5 Ex 1-9 1.08 1.53 0.56 A 1.4 ◯ ◯ 792 46.5 24.9 Ex 1-10 —1.41 0.39 D 1.8 ◯

759 45.4 24.5 Ex 1-11 1.32 1.17 0.62 C 1.6 ◯ ◯ 701 53.8 24.8 Ex 1-121.32 1.17 0.62 B 1.9 ◯

828 43.6 24.8 Ex 1-13 1.47 1.122 0.60 C 2.2

749 44.7 23.5 Ex 1-14 — 1.86 0.56 A 1.7 ◯ ◯ 727 44.0 23.8 Ex 1-15 2.450.51 0.72 A 1.9 ◯ ◯ 790 43.6 22.5 Ex 1-16 3.05 — 0.70 B 2.6

783 43.5 22.1 Ex 1-17 1.47 1.53 0.84 C 1.8 ◯ ◯ 816 43.3 21.6 Ex 1-183.68 — 0.93 D 2.1 ◯

712 43.5 21.7 Ex 1-19 3.14 1.84 1.22 A 2.2

815 41.6 19.6 “Ex” means Example according to the present invention.

TABLE 1-2 Alloying elements Bending ID Ni Co Si property YS EC SR numbermass % mass % mass % Step R GW BW MPa % IACS % C Ex 1-1 0.22 0.15 0.65 C1.1 ◯ ◯ 492 29.1 23.1 C Ex 1-2 4.12 1.44 0.95 C 1.2 ◯ ◯ 749 24.3 27.1 CEx 1-3 — 1.12 0.08 D 1.3 ◯ ◯ 498 38.6 36.5 C Ex 1-4 2.82 — 1.72 C 1.2 ◯◯ 752 18.5 25.0 C Ex 1-5 1.50 2.50 0.9  E 0.5 X X 812 47.0 23.9 C Ex 1-61.50 1.20 1.6  F 0.6 X X 786 44.9 30.2 C Ex 1-7 — 1.02 0.35 E 0.7 X X640 56.2 26.3 C Ex 1-8 2.50 — 0.59 F 0.5 X X 795 45.6 26.3 C Ex 1-9 2.72— 0.62 E 0.3 X X 835 39.0 35.9 “C Ex” means Comparative Example.

As shown in Table 1-1, Examples 1-1 to 1-19 according to the presentinvention were excellent in the bending property, the proof stress, theelectrical conductivity, and the stress relaxation resistance.

On the contrary, as shown in Table 1-2, when the requirements of thepresent invention were not satisfied, results were poor in any of theproperties.

That is, since Comparative Example 1-1 had a too small total amount ofNi and Co, the density of the compounds (precipitates) that contributeto precipitation hardening was decreased, and the mechanical strengthwas poor. Further, Si that did not form a compound with Ni and/or Co,formed a solid solution in the metal texture excessively, and thus theelectrical conductivity was poor. Comparative Example 1-2 had a toolarge total amount of Ni and Co, and thus the electrical conductivitywas poor. Comparative Example 1-3 had a too small amount of Si, and thusthe mechanical strength was poor. Comparative Example 1-4 had a toolarge amount of Si, and thus the electrical conductivity was poor.Comparative Examples 1-5 to 1-9 each had a too low R value, and werepoor in the bending property.

Example 2

With respect to the copper alloys having the compositions shown in thecolumn of alloying elements in Table 2, with the balance of Cu andunavoidable impurities, test specimens of copper alloy sheet materialsof Examples 2-1 to 2-17 according to the present invention andComparative Example 2-1 to 2-3 were produced in the same manner as inExample 1, and the test specimens were subjected to examination of theproperties in the same manner as in Example 1.

The results are shown in Table 2.

TABLE 2 Alloying elements Bending ID Ni Co Si Other elements property YSEC SR number mass % mass % mass % mass % Step R GW BW MPa % IACS % Ex2-1 0.50 1.00 0.36 0.15Sn, 0.2Ag D 1.6 ◯ ◯ 675 53.4 23.3 Ex 2-2 1.000.50 0.38 0.03Zr, 0.05Mn A 2.1 ◯ ◯ 737 50.2 20.7 Ex 2-3 — 0.80 0.450.32Ti, 0.21Fe C 1.7 ◯ ◯ 712 51.7 21.8 Ex 2-4 0.50 1.50 0.35 0.2Ag,0.05B, 0.1Mg B 1.4 ◯ ◯ 740 51.2 23.4 Ex 2-5 0.80 1.20 0.42 0.14Mg,0.15Sn, 0.3Zn C 1.8 ◯ ◯ 735 49.9 19.6 Ex 2-6 1.00 1.00 0.48 0.23Cr,0.14Mg, 0.10P D 1.6 ◯ ◯ 760 48.5 21.8 Ex 2-7 2.32 — 0.65 0.2Hf, 0.2Zn B1.9 ◯ ◯ 785 39.8 24.4 Ex 2-8 0.90 1.70 0.61 0.04Zr, 0.42Ti, 0.11Mg D 2.2◯ ◯ 811 45.4 21.2 Ex 2-9 1.10 1.50 0.55 0.15Sn, 0.2Ag C 1.7 ◯ ◯ 795 44.522.6 Ex 2-10 — 1.38 0.38 0.11Mg, 0.32Zn B 1.6 ◯ ◯ 817 44.0 23.2 Ex 2-111.35 1.15 0.61 0.14Mg, 0.15Sn, 0.3Zn C 1.9 ◯ ◯ 758 51.9 21.5 Ex 2-121.35 1.15 0.61 0.22Cr, 0.05Mn A 2.2 ◯ ◯ 789 41.7 22.5 Ex 2-13 1.5 1.1 0.59 0.11Mg, 0.32Zn, 0.5Ti A 2.1 ◯ ◯ 806 43.3 22.2 Ex 2-14 — 1.82 0.550.14Mg, 0.15Sn, 0.3Zn C 1.7 ◯ ◯ 786 42.4 20.5 Ex 2-15 2.50 0.50 0.710.23Cr, 0.11Mg, 0.32Zn B 1.4 ◯ ◯ 788 41.7 20.2 Ex 2-16 3.11 — 0.69 0.20Cr, 0.2Sn, 0.2Ag B 1.8 ◯ ◯ 814 42.2 18.8 Ex 2-17 1.50 1.50 0.82 0.04Mn,0.2Fe, 0.1Hf C 2 ◯ ◯ 803 41.7 19.2 C Ex 2-1 2.32 — 0.65 0.62Hf, 1.55Zn B1.2 ◯ ◯ 728 27.9 24.4 C Ex 2-2 1.35 1.15 0.61 0.42Mg, 0.82Sn, 1.53Zn C1.3 ◯ ◯ 758 26.9 21.5 C Ex 2-3 — 1.82 0.55 0.61Mn, 0.32Cr, 1.42Ag D 1.2◯ ◯ 786 24.9 20.5 “Ex” means Example according to the present invention,and “C Ex” means Comparative Example.

As shown in Table 2, Examples 2-1 to 2-17 according to the presentinvention were excellent in the bending property, the proof stress, theelectrical conductivity, and the stress relaxation resistance.

On the contrary, when the requirements of the present invention were notsatisfied, results were poor in any of the properties. That is, sinceComparative examples 2-1, 2-2, and 2-3 (each of which was a comparativeexample against the invention according to the item (3) above) each hada too large content of elements other than Ni, Co, and Si, they werepoor in the electrical conductivity.

Example 3

By using the copper alloy having the composition shown in Table 3, withthe balance being Cu and inevitable impurities, the ingot was subjectedto a homogenization heat treatment at 1,020 to 700° C. for 10 minutes to10 hours, followed by hot-rolling as shown in Table 4, water cooling,face milling, cold-rolling at a working ratio of 50% to 99%, a heattreatment of maintaining at 600 to 900° C. for 10 seconds to 5 minutes,cold-working at a working ratio of 5% to 55%, and a final solution heattreatment of maintaining at 750 to 1,000° C. for 5 seconds to 1 hour.Then, the resultant sheet was subjected to an aging precipitation heattreatment at 350 to 600° C. for 5 minutes to 20 hours, finish rolling ata working ratio of 2 to 45%, and temper annealing of maintaining at 300to 700° C. for 10 seconds to 2 hours, to produce a test specimen. Theproperties were examined in the same manner as in Example 1. The resultsare shown in Table 4.

TABLE 3 Additive elements Ni Co Si Sn Zn Mg Cr mass % 2.71 0.32 0.760.17 0.31 0.07 0.17

TABLE 4 Hot-working Working temperature/working ratio per pass 1st pass2nd pass 3rd pass 4th pass Ex 3-1 (P + 100)° C./33% (P + 80)° C./33%(P + 50)° C. s/33% → Air cooling (P − 50)° C./15% Ex 3-2 (P + 130)°C./28% (P + 120)° C./28% → Air cooling (P − 50)° C./20% (P − 70)° C./20%Ex 3-3 (P + 130)° C./30% (P + 120)° C./30% (P + 110)° C./30% (P + 100)°C./30% → Water cooling Ex 3-4 (P + 130)° C./27% (P + 110)° C./30% (P +90)° C./30% → Water cooling (P − 150)° C./20% C Ex 3-1 (P + 100)° C./30%(P + 80)° C./31% (P + 60)° C./32% (P + 40)° C./33% C Ex 3-2 (P + 80)°C./15% (P + 70)° C./15% (P + 50)° C./15% → Air cooling (P − 50)° C./15%C Ex 3-3 (P + 130)° C./27% (P + 110)° C./30% (P + 90)° C./30% → Watercooling (P − 50)° C./35% C Ex 3-4 (P − 50)° C./15% (P − 70)° C./15% (P −80)° C./15% (P − 100)° C./15% Hot-working Bending Workingtemperature/working ratio per pass property YS EC SR 5th pass 6th pass7th pass 8th pass R GW BW MPa % IACS % Ex 3-1 (P − 80)° C./15% (P −110)° C./15% — — 1.6 ◯ ◯ 738 49.0 21.6 Ex 3-2 — — — — 1.9 ◯ ◯ 707 40.224.2 Ex 3-3 (P − 80)° C./20% (P − 100)° C./20% (P − 110)° C./20% (P −130)° C./20% 2.2 ◯ ◯ 780 45.9 21.0 Ex 3-4 (P − 170)° C./20% (P − 190)°C./20% (P − 210)° C./20% — 1.7 ◯ ◯ 785 44.9 22.4 C Ex 3-1 — — — — 0.8 XX 796 46.0 23.5 C Ex 3-2 (P − 80)° C./15% (P − 110)° C./15% — — 0.6 X X821 39.3 29.6 C Ex 3-3 (P − 70)° C./35% (P − 80)° C./35% — — 0.7 X X 78839.2 25.8 C Ex 3-4 (P − 110)° C./15% (P − 130)° C./15% — — 0.5 X X 77937.8 25.8 “Ex” means Example according to the present invention, and “CEx” means Comparative Example.

As shown in Table 4, Examples 3-1 to 3-4 according to the presentinvention were excellent in the bending property, the proof stress, theelectrical conductivity, and the stress relaxation resistance.

On the contrary, when the requirements of the present invention were notsatisfied, results were poor in any of the properties. That is, sinceComparative Examples 3-1 to 3-4 were conducted under the conditions onthe hot-working outside the ranges defined in the present invention, therespective value of R as defined in the present invention did notsatisfy the predetermined value, and they were poor in the electricalconductivity.

As described in the above, according to the present invention, quitefavorable characteristics can be realized, which are required of, forexample, materials for vehicle-mounted parts, such as connectormaterials, and materials for electrical/electronic equipments(particularly, substrate material for the parts).

Next, in order to clarify the difference between copper alloy sheetmaterials produced under the conventional production conditions and thecopper alloy sheet material according to the present invention, copperalloy sheet materials were produced under the conventional conditions,and evaluations of the same characteristic items as described above wereconducted. The working ratio was adjusted so that, unless otherwisespecified, the thickness of the respective sheet material would be thesame as the thickness in the examples described above.

(Comparative Example 101) . . . Conditions Described in JP-A-2009-007666

An alloy formed by blending the same metal elements as those in Example1-1, with the balance of Cu and inevitable impurities, was melted in ahigh-frequency melting furnace, followed by casting at a cooling speedof 0.1 to 100° C./sec, to obtain an ingot. The resultant ingot wasmaintained at 900 to 1,020° C. for 3 minutes to 10 hours, followed bysubjecting to hot-working, quenching in water, and then surface millingto remove oxide scale. For the subsequent steps, use was made of thetreatments/workings of the following steps A-3 and B-3, to produce acopper alloy c01.

The production steps included one, two times or more solution heattreatments. Herein, the steps were divided into those before and afterthe final solution heat treatment, so that the steps up to theintermediate solution treatment are designated as Step A-3, while thesteps after the intermediate solution treatment are designated as StepB-3. With regard to the working ratio and the number of passes in thehot-working, the hot working was conducted by employing the conditionsthat were usually used at the time of filing of the present application,that is, the conditions of temperature 800 to 1,020° C., one-passworking ratio 35 to 40%, and the number of passes 2 to 5 times.

Step A-3: Cold working at a cross-sectional area reduction ratio of 20%or greater, a heat treatment at 350 to 750° C. for 5 minutes to 10hours, cold working at a cross-sectional area reduction ratio of 5 to50%, and a solution heat treatment at 800 to 1,000° C. for 5 seconds to30 minutes.

Step B-3: Cold working at a cross-sectional area reduction ratio of 50%or less, a heat treatment at 400 to 700° C. for 5 minutes to 10 hours,cold working at a cross-sectional area reduction ratio of 30% or less,and temper annealing at 200 to 550° C. for 5 seconds to 10 hours.

Test specimen c01 thus obtained was different from the examplesaccording to the present invention in terms of the second hot-rollingstep, whether conducted or not, among the hot-rolling conditions in theproduction conditions, and resulted in not satisfying the requiredcharacteristics for the bending property due to the too low R value.

(Comparative Example 102) ... Conditions Described in JP-A-11-335756

A copper alloy having the same composition as in Example 1-1 was meltedin the air under charcoal coating in a kryptol furnace, followed bycasting in a book mold, to produce an ingot with size 50 mm×80 mm×200mm. The resultant ingot was heated to 930° C., followed by hot-rollingto thickness 15 mm, and then immediate quenching in water. In order toremove the oxide scale at the surface of the hot-rolled sheet, thesurface was machined with a grinder. The resultant sheet was coldrolled, followed by subjecting to a heat treatment at 750° C. for 20seconds, cold-rolling at 30%, and precipitation annealing at 480° C. for2 hours, to give a material adjusted in sheet thickness, which wassupplied to the test (c02). With regard to the working ratio and thenumber of passes in the hot-rolling, the hot rolling was conducted byemploying the conditions that were usually used at the time of filing ofthe present application, that is, the conditions of a working ratio 35to 40%, and the number of passes 2 to 5 times.

Test specimen c02 thus obtained was different from the examplesaccording to the present invention in terms of the heat treatment [Step7] and the cold-working [Step 8], whether conducted or not, and thesecond hot-rolling step, whether conducted or not, among the hot-rollingconditions in the production conditions, and resulted in not satisfyingthe bending property due to the too low R value.

(Comparative Example 103) . . . Conditions described in JP-A-2008-223136

The copper alloy shown in Example 1 was melted, followed by casting witha vertical continuous casting machine. From the thus-obtained ingot(thickness 180 mm), a sample with thickness 50 mm was cut out, and thissample was heated to 950° C., followed by extracting, and then startinghot-rolling. At that time, the rolling ratio in the temperature range of950 to 700° C. was 60% or higher, and the pass schedule was set so as toconduct rolling even in the temperature range of lower than 700° C. Thefinal pass temperature of hot-rolling was between 600 and 400° C. Thetotal hot-rolling ratio from the ingot was about 90%. After thehot-rolling, the oxide layer at the surface layer was removed bymechanical polishing (surface milling).

Then, after conducting cold-rolling, the sample was subjected to asolution treatment. The temperature change at the time of the solutiontreatment was monitored with a thermocouple attached to the samplesurface, and the time period for temperature rise from 100 to 700° C. inthe course of temperature rising was determined. The end-pointtemperature was adjusted in the range of 700 to 850° C., depending onthe alloy composition, so that the average grain size (a twin boundarywas not regarded as the grain boundary) after the solution treatmentwould be 10 to 60 μm, and the retention time period in the temperaturerange of 700 to 850° C. was adjusted in the range of 10 sec to 10 min.Then, the sheet material obtained after the solution treatment wassubjected to intermediate cold-rolling at the rolling ratio, followed byaging. The aging temperature was set to a material temperature of 450°C., and the aging time period was adjusted to the time at which thehardness reached the maximum upon the aging at 450° C., depending on thealloy composition. The optimum solution treatment conditions and theoptimum aging time period had been found by preliminary experiments inaccordance with the alloy composition. Then, finish cold-rolling wasconducted at the rolling ratio. Samples that had been subjected to thefinish cold-rolling were then further subjected to low-temperatureannealing of placing the sample in a furnace at 400° C. for 5 minutes.Thus, test specimen c03 was obtained. Surface milling was conducted inthe mid course, as necessary, and thus the sheet thickness of the testspecimen was set to 0.2 mm. The principal production conditions are asdescribed below.

[Conditions of Example 1 of JP-A-2008-223136]

Hot-rolling ratio at below 700° C. to 400° C.: 56% (one pass)

Cold-rolling ratio before solution treatment: 92%

Cold-rolling ratio for intermediate cold-rolling: 20%

Cold-rolling ratio for finish cold-rolling: 30%

Time period for temperature rise from 100° C to 700° C.: 10 seconds

Test specimen c03 thus obtained was different from Example 1 in terms ofthe cooling process, whether conducted or not, between the first stepand the second step in the hot-rolling, the working ratio of the secondstep, and the heat treatment [Step 7] and the cold-working [Step 8],whether conducted or not, in the production conditions, and resulted innot satisfying the bending property due to the too low R value.

(Comparative Example 104) Conditions of Comparative Example Described inJP-A-2008-223136

Test specimen c04 was produced in the same manner as in ComparativeExample 103, except that the working conditions of the following itemswere changed as described below.

[Conditions of Comparative Example 1 of JP-A-2008-223136]

Hot-rolling ratio at below 700° C. to 400° C.: 17% (one pass)

Cold-rolling ratio before solution treatment: 90%

Cold-rolling ratio for intermediate cold-rolling: 20%

Cold-rolling ratio for finish cold-rolling: 30%

Time period for temperature rise from 100° C. to 700° C.: 10 seconds

Test specimen c04 thus obtained was different from Example 1 in terms ofthe cooling process, whether conducted or not, between the first stepand the second step in the hot-rolling, and the heat treatment [Step 7]and the cold-working [Step 8], whether conducted or not, in theproduction conditions, and resulted in not satisfying the bendingproperty due to the too low R value.

REFERENCE SIGNS LIST

-   1 Test specimen with an initial stress applied thereon-   2 Test specimen after removing the load-   3 Test specimen without any stress applied thereon-   4 Test bench

1-7. (canceled)
 8. A copper alloy sheet material, having an alloycomposition containing any one or two of Ni and Co 0.5 to 5.0 mass % intotal, Si 0.1 to 1.5 mass %, and optionally at least one selected fromthe group consisting of Sn, Zn, Ag, Mn, B, P, Mg, Cr, Fe, Ti, Zr, and Hf0.005 to 2.0 mass % in total, with the balance being copper andunavoidable impurities, having an R value of 1 or greater, which isdefined by:R=([BR]+[RDW]+[W])/([C]+[S]+[B]) wherein [BR], [RDW], [W], [C], [S], and[B] represent an area ratio of crystal texture orientation component ofBR orientation {3 6 2}<8 5 3>, RD-rotated-cube orientation {0 1 2}<1 00>, cube orientation {1 0 0}<0 0 1>, copper orientation {1 2 1}<1 1 1>,S-orientation {2 3 1}<3 4 6>, and brass orientation {1 1 0}<1 1 2>,respectively, in crystal orientation analysis in an EBSD (electron backscatter diffraction) analysis, and having a proof stress of 500 MPa orgreater, and an electrical conductivity of 30%IACS or higher.
 9. Aconnector, which is composed of the copper alloy sheet materialaccording to claim
 8. 10. A method of producing the copper alloy sheetmaterial according to claim 8, comprising the steps of: subjecting acopper alloy having the alloy composition to give the copper alloy, tocasting [Step 1], a homogenization heat treatment [Step 2], hot-working[Step 3], cold-rolling [Step 6], a heat treatment [Step 7], cold-rolling[Step 8], and a final solution heat treatment [Step 9], in this order,and then subjecting the resultant copper alloy to an aging precipitationheat treatment [Step 10], BIRCH, STEWART, KOLASCH & BIRCH, LLPMSW/CAM/kec wherein the hot-working [Step 3] is carried out, by firstconducting two or more passes of hot-rolling at a temperature from(P+30)° C. to 1,020° C. (in which P (° C.) represents the complete solidsolution temperature of solute atoms) at a working ratio per pass of 25%or higher, cooling to a temperature (P−30)° C. or lower, and thenconducting two or more passes of hot-rolling at a temperature from 400°C. to (P−30)° C. at a working ratio per pass of 25% or lower, whereinthe cold-rolling [Step 6] is carried out at a working ratio of 50 to99%, wherein the heat treatment [Step 7] is carried out by maintainingat 600 to 900° C. for 10 seconds to 5 minutes, and wherein thecold-working [Step 8] is carried out at a working ratio of 5 to 55%. 11.The method of producing the copper alloy sheet material according toclaim 10, wherein cold-rolling [Step 11] and temper annealing [Step 12]are conducted in this order, after the aging precipitation heattreatment [Step 10].